The present invention relates generally to a testing method and apparatus for verifying the correct assembly of a circuit, such as a telephonic switch, having circuit elements connectable together by connecting elements. More particularly, the present invention relates to a method, and an associated apparatus, for verifying correct connection together of circuit elements by way of connecting elements in a circuit having redundant circuit portions.
Information-related technologies oftentimes utilize devices capable of acting upon data. Data is, for instance, transferred, stored, transmitted, received, or otherwise communicated, during operation of the devices. Such devices must be capable of dependably performing the functions for which they are intended. Improper operation of, or failure of, such devices, could result in the irretrievable loss of the data being operated upon by such devices. Care is taken, therefore, in the design and construction of the circuitry of such devices to ensure that the circuitry is as reliable as possible.
One manner by which to increase the reliability of such circuitry and minimize the possibility of the loss of data due to failure of the circuitry is to provide redundancy to the circuitry. Redundant circuitry is operable simultaneously to receive the same input data, perform the same operations upon the data, and to generate the same output data. The likelihood of concurrent failure of the redundant circuitry is typically less than the likelihood of failure of circuitry which is not provided with redundancy. Accordingly, the dependability of devices utilizing the redundant circuitry is typically better than devices without redundant circuitry. By increasing the amount of redundancy, that is, by providing multiply-redundant circuitry, the likelihood of concurrent failure of all of the multiply-redundant circuitry is further reduced.
A telephonic switch is exemplary of an electronic circuit utilized in the communication of data. A telephonic switch is an essential part of a telephonic communication system and is operable to provide connections which permit communication links to be effectuated between calling and receiving stations of the telephonic communication system.
While the function of a telephonic switch may be fairly simply visualized, telephonic switches utilized in commercial telephonic systems are fairly complex devices capable of forming concurrent communication links between many pairs, or more, of calling and receiving stations. Significant numbers of communication signals, each containing data, are input to, and output from, a typical, telephonic switch during operation thereof.
An example of such a telephonic switch is disclosed in the aforementioned U.S. Pat. No. 5,347,513, the disclosure of which is incorporated herein by reference.
The switch disclosed in U.S. Pat. No. 5,347,513 includes redundant circuitry portions for reasons including those discussed above. Other telephonic switches and, more generally, other types of circuitry utilized in information-related, and other, technologies similarly utilize redundant circuitry portions.
In normal operation of the telephonic switch disclosed in U.S. Pat. No. 5,347,513, data input to the switch is transmitted along each of three redundant circuitry portions. As the data is acted upon during operation of the switch, a polling of the values of acted-upon data is performed. Values of acted-upon data of a redundant circuit portion which is faulted or failed shall likely be dissimilar to the values of the acted-upon data of unaffected redundant circuitry portions. When such a dissimilarity is detected, the affected circuitry portion can be isolated from unaffected circuitry portions. Appropriate repair or replacement of the affected circuitry portion may take place when convenient or otherwise possible. In the meantime, the unaffected circuitry portions remain operable.
Assembly of a circuit, such as the above-noted telephonic switch, requires the redundant circuit portions each to be connected at their respective inputs and outputs, to the same circuit locations. Additionally, a single redundant circuit portion might well be disposed upon several separate circuit boards. During assembly of the circuit, a circuit assembler must properly connect together the circuit boards, such as by way of a physical or optical coupler, which form each of the redundant circuit portions. As corresponding connections together of the circuit boards of each of the redundant circuit portions must be performed by the circuit assembler, the circuit assembler is typically required to make many connections during assembly of the circuit.
For example, as noted above, the telephonic switch disclosed in the aforementioned U.S. Pat. No. 5,347,513, utilizes a three-fold circuit redundancy. The circuit assembler is therefore required to interconnect a fairly significant number of circuit boards during assembly of the telephonic switch. Other switches, as well as other circuits having redundant circuitry portions, similarly typically also require a significant number of interconnections during their assembly.
Because of the significant number of interconnections required to be performed during assembly, a circuit assembler might fail to properly interconnect all of the circuit portions in the proper manner. If the circuit assembler instead interconnects circuit portions of different ones of the redundant circuit portions, such misconnection might not be detected during normal testing of the circuit as an operable circuit might still be formed.
However, upon failure of, or fault in, one of the circuit portions, the misconnection might result in isolation or removal of an unaffected, rather than an affected, circuit portion out of the circuit. Such an occurrence would not only defeat the utility of redundant circuitry portions, but could also cause the irretrievable loss of data being acted upon by the telephonic switch or other circuit.
A test by which to determine proper connection of the various elements of a circuit having redundant circuit portions would therefore be advantageous. Misconnection of circuit elements could be detected, and appropriate corrective actions could be taken.
It is in light of this background information related to circuits having redundant circuitry portions, such as a telephonic switch, that the significant improvements of the present invention have evolved.